Conventionally, it is known that a non-volatile memory such as a flash memory for the use in a storage apparatus has a limitation on the number of rewrite cycles. Here, the number of rewrite cycles can be counted by adding a cycle in which a memory cell in an initial state is put into a state in which data is stored and returned to the initial state again, as one rewrite cycle. In such a non-volatile memory, data is rewritten by erasing and writing in units of pages. Therefore, the number of rewrite cycles is added up for each page. There has been proposed a storage apparatus having reliability enhanced by achieving wear leveling to swap data of a page in which this number of rewrite cycles is larger for data of a page in which the number of rewrite cycles is smaller (e.g., see Patent Literature 1).